Radiographic techniques in renal parenchymal disease

In his or her practice, the nephrologist usually has a substantial number of patients on dialysis for chronic renal failure. The longer a patient remains on either peritoneal dialysis or hemodialysis, the more at risk he or she is of developing acquired cystic disease of the kidney and renal cell carcinoma. Due to recent developments such as lower osmolar intravenous contrast media, sonography, and magnetic resonance imaging, the radiologist has the ability to assess the kidney in chronic renal failure with a growing number of less-invasive modalities. The lower osmolar agents appear to be less toxic to the kidney. Thus, they can be used when the benefit of the information obtained from a necessary procedure, eg, computed tomography or coronary arteriography, surpasses the risk. Duplex Doppler sonography can assess the pressure of flow in the arcuate vessels of the kidney with measurements of the resistive index. The resistive index is a proven tool for assessing rejection of the renal allograft--another newer application is in the diagnosis of obstruction. An elevated resistive index found in a kidney with a dilated collecting system confirms the diagnosis of obstruction. Studies are being made on its application in other renal disease processes as well.